Purification arrangements and methods for gas pipeline systems

ABSTRACT

A purification arrangement for a gas pipeline system includes a pressure vessel and at least first and second purification assemblies in the interior of the pressure vessel. A gas flow may be established through the pressure vessel, and the gas may pass through the first purification assembly and the second purification assembly to remove liquid and/or solid particulates from the gas. At least one of the first and second purification assemblies includes a separator assembly having one or more separators which removes particulates and a shell mounted to one or more of the separators to collect and contain the removed particulates.

DISCLOSURE OF THE INVENTION

Natural gas and other gases transmitted through pipeline systems maycarry many types of particulates, including liquid droplets and/or solidparticles. The gas may be the source of the particulates. For example,gas entering the pipeline system from a gas treatment facility after ithas been extracted from a well may still be laden with particulates. Orthe particulates may be generated within the pipeline system itself. Forexample, solid particles may be generated by corrosion and abrasionwithin the pipeline system. Liquid droplets may arise from condensationor as residues of liquid cleaners for the pipeline system. Many of theseparticulates are harmful to the components of the pipeline system andthe personnel who operate and service the pipeline system. For example,the gas may carry black powder, a general term used to describe a hostcorrosion-related particulate contaminants, that can be erosive, toxic,and/or chemically reactive with air, i. e., pyrophoric.

The present invention relates to purification arrangements and methodsfor removing particulates from gas flowing through the pipeline system.Embodiments of the invention may include a pressure vessel having aninlet and an outlet connected to the pipeline system. The pressurevessel may contain at least two purification assemblies, and the gas maybe directed through the pressure vessel, where the purificationassemblies remove particulates from the gas.

A wide variety of purification assemblies may be used to remove theparticulates. For example, one or more of the purification assembliesmay comprise a filter assembly. Each filter assembly may include one ormore filter elements, and each filter element may include a porousfilter medium. As the gas flows through the pressure vessel, it passesthrough the filter medium, and the particulates carried by the gas aretrapped on the surface of and/or within the filter medium. Further, atleast one of the purification assemblies comprises a separator assembly.Each separator assembly may include one or more separators which removeparticulates from the gas without the use of a porous filter medium. Forexample, a separator may slow the velocity of the gas and allow theparticulates to settle from the gas, or a separator may deflect theparticulates from the principal gas flow stream, causing the gas and theparticulates to separate from one another. In any event, thepurification assemblies remove a significant portion of theparticulates, and gas leaving the pressure vessel has significantlyfewer particulates than gas entering the pressure vessel.

SUMMARY OF THE INVENTION

In accordance with one aspect of the invention, purificationarrangements for a gas pipeline system may comprise a pressure vesseland at least first and second purification assemblies. The pressurevessel may include an interior, a gas inlet, and a gas outlet and maydefine a gas flow path through the interior of the pressure vesselbetween the gas inlet and the gas outlet. Both the first and secondpurification assemblies may be located in the gas flow path in theinterior of the pressure vessel between the gas inlet and the gasoutlet. The second purification assembly may be positioned in theinterior of the pressure vessel between the first purification assemblyand the gas outlet. At least one of the first and second purificationassemblies includes separator assembly, and the separator assembly hasone or more separators which remove particulates from the gas. Theseparator further includes a shell mounted to one or more of theseparators to contain the particulates removed by the separator.

In accordance with another aspect of the invention, purificationarrangements for a gas pipeline may comprise a pressure vessel, a filterassembly and a separator assembly. The pressure vessel may include aninterior, a gas inlet, and a gas outlet and may define a gas flow paththrough the interior of the pressure vessel between the gas inlet andthe gas outlet. The filter assembly, which may be located in the gasflow path in the interior of the pressure vessel, may comprise aplurality of filter elements, and each filter element may have a porousfilter medium. The filter medium filters particulates from the gasflowing through each filter element. The separator assembly may belocated in the gas flow path in the interior of the pressure vesselbetween the filter assembly and the gas inlet of the pressure vessel.The separator assembly may include one or more separators, and eachseparator removes particulates from gas flowing through the separatorassembly. The separator assembly further includes a shell mounted to oneor more of the separators to contain the particulates removed by theseparator.

In accordance with another aspect of the invention, methods for removingparticulates from a gas flowing in a gas pipeline system may compriseestablishing a flow of gas through a pressure vessel, includingdirecting the gas through a first purification assembly and a secondpurification assembly in the interior of the pressure vessel to removeparticulates from the gas. Directing the gas through the first andsecond purification assemblies includes directing the gas through one ormore separators which remove particulates from the gas and containingthe particulates removed by the separators in a shell mounted to theseparators. Each method also comprises terminating the flow of gasthrough the pressure vessel and servicing at least one of the first andsecond purification assemblies, including removing from the pressurevessel the separator assembly and the shell containing the particulates.

Purification arrangements and methods embodying one or more aspects ofthe invention have many advantages. The first and second purificationassemblies are highly effective for removing particulates from the gas,so the gas returning to the pipeline system from the pressure vessel hasfar fewer particulates, e.g., may be largely free of solid particles andliquid droplets, compared to the gas entering the pressure vessel.Further, the purification assemblies may be adjusted or restructured toaccommodate varying gas flow conditions in the pipeline withoutmodification of the pressure vessel. In addition, with the shell mountedto one or more of the separators, the purification assemblies may beserviced, e.g., cleaned and/or replaced, much more quickly and safely.For example, by containing the particulates within the shell, theseparation assembly may be removed from the pressure vessel withoutexposing the service personnel to the potentially toxic, even chemicallyreactive, particulate matter removed from the gas by the separators. Forsome embodiments, the shell may be liquid-tight and may be filled withwater and/or any other suitable inhibitor before removal, furtherprotecting the service personnel by preventing the particulates fromcontacting the air upon removal. Further, by containing the particulateswithin the shell, the pressure vessel remains much cleaner, reducing thedowntime for servicing and replacing the separator assembly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side view of purification arrangement with portions of thepressure vessel and shell cut away.

FIG. 2 is an oblique view of a filter assembly.

FIGS. 3 a and 3 b are oblique top and bottom views of a separatorassembly.

FIG. 4 is an oblique view of a casing for the separator assembly of FIG.3.

FIG. 5 is an exploded oblique view of an openable/closeable barrier.

DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION

Purification arrangements embodying the invention may be configured in awide variety of different ways. For example, the purificationarrangement 10 shown in FIG. 1 may comprise a pressure vessel 11 and twoor more purification assemblies 12, 13 located in the interior of thepressure vessel 11. The pressure vessel 11 may have a gas inlet 15 and agas outlet 16 coupled to a gas pipeline system (not shown) and maydefine a gas flow path through the interior of the pressure vesselbetween the gas inlet 15 and the gas outlet 16. The purificationassemblies 12, 13 are positioned in the gas flow path between the gasinlet 15 and the gas outlet 16. Natural gas or any other gas passingthrough the gas pipeline system is directed through the pressure vessel11 from the gas inlet 15 through one of the purification assemblies 12and then the other purification assembly 13 to the gas outlet 16. Asignificant portion of the particulates, e.g., almost all solidparticles and most of the liquid droplets, entrained in the gas as itenters the gas inlet 15 is removed by the purification assemblies 12,13, so the gas leaving the pressure vessel 11 is largely free ofparticulates.

The pressure vessel may be configured in any of numerous ways. Forexample, the pressure vessel may have a configuration similar to ascraper trap/launcher vessel used to service the interior of thepipeline. The pressure vessel may have an elongate, generallycylindrical structure and the axis may extend horizontally, or it mayextend vertically or at any angle between horizontal and vertical. Thepressure vessel may be formed as a unitary structure or in a pluralityof sections joined together in a fluid-tight manner. Further, thepressure vessel may be constructed to withstand the design pressures andtemperatures appropriate for the pipelines of the pipeline system. Forexample, for many natural gas pipeline systems, the design pressure maybe in the range from about 30 barg or less to about 75 barg or more,e.g., about 60 barg, and the design temperature may be in the range fromabout minus 40° C. to about 100° C., e.g., about 70° C. For manyembodiments, the pressure vessel may be formed from a metal and is quitelarge and heavy. The gas inlet and the gas outlet of the pressure vesselmay be on opposite axial ends of the vessel, or one may be on an end andthe other may be on the side of the vessel, or both may be on the sideof the vessel facing in the same or different directions. In addition tothe gas inlet and the gas outlet, a variety of other ports may beprovided at various locations on the vessel, including ports forpressure protection, purging, flooding, depressurization, and/ordraining and for pressure drop and level control. Further, the pressurevessel may include one or more hatches or other covers on the ends orside of the pressure vessel to allow access to the interior for servicepersonnel and/or equipment, including removal and installation of thepurification assemblies. In the embodiment of FIG. 1, the pressurevessel 11 may be oriented horizontally and supported by two or morestands 17 and may include a gas outlet 16 at one end of the pressurevessel 11, a gas inlet 15 in the side of the pressure vessel 11 nearerthe other end, e.g., along the top of the pressure vessel 11, and acover such as a quick opening hatch 20 hinged at the other end of thepressure vessel 11. The hatch 20 may be large enough to swing open andprovide access along the entire inner diameter of the pressure vessel11, facilitating installation and removal of the purificationassemblies. Alternatively, a cover may be bolted to the end of thepressure vessel, again providing access along the entire inner diameterwhen the cover is removed and facilitating removal and installation ofone or more of the purification assemblies. The pressure vessel 11 mayalso be provided with one or more purge gas inlets 21 and one or moregas discharge outlets 22 communicating between the interior and exteriorof the pressure vessel 11.

The purification assemblies may be configured in a wide variety of waysto remove particulates, including liquid particulates and/or solidparticulates, entrained in the gas. For example, depending on thespecific type of particulates present in the gas of the pipeline system,at least one or all of the purification assemblies in the pressurevessel may be a separator assembly and one or more of the purificationassemblies in the pressure vessel may be a filter assembly. For manypipeline systems, black powder may be a typical particulate entrained inthe gas. Black powder is a general term used to describe a host ofcorrosion related contaminants in pipelines that transport natural gas,hydrocarbon condensates, liquefied petroleum gas, and other gases. Thechemical and physical composition of black powder may varysignificantly. It can be a dry powder, a liquid suspension, and/or anintermediate sticky sludge. The dry powder may include iron oxides, ironsulfides, and iron carbonates and may be fine, even submicron in size.For example, about 70% of the dry black powder particles may be about 10microns or less in size, and the total loading may be in the range ofabout 5 to 30 grams/MMSCF during normal operation of the pipeline,although after a scraping operation the total loading may increase by afactor of up to 20 or more. Binder material present in the pipelines,e.g., parafins, asphaltenes, glycols, and/or lubricants, may hold someof the black powder particles together to form larger agglomerates.Additional solids, e.g., sand and/or silt, frequently accompany theblack powder entrained in the gas. Consequently, for many, but not all,of the embodiments, one of the purification assemblies, e.g., the mostdownstream purification assembly in the pressure vessel, may be a filterassembly arranged to remove finer particulates, and another purificationassembly, e.g., the most upstream purification assembly, may be aseparator assembly arranged to remove liquid particulates and/or largersolid particulates and agglomerates. For example, in the purificationarrangement 10 shown in FIG. 1, the purification assembly 12 coupledmore closely to the gas inlet 15 may be a separator assembly 23 and thepurification assembly 13 coupled more closely to the gas outlet 16 maybe a filter assembly 24.

The filter assembly may be configured in any of numerous ways and mayinclude one or more filter elements. For many embodiments, the filterassembly 24 may comprise a filter bundle assembly having an array offilter elements 25, as shown in FIG. 2. The filter elements may have anyof a wide variety of shapes and sizes. For example, each filter element25 may have a hollow, generally cylindrical shape, may include a blindend and an open end fluidly communicating with the interior of thehollow element, and may be arranged for gas flow outside-in orinside-out through element. The filter elements 25 may include a widevariety of porous filter media 26 for removing particulates from thegas. The porous filter medium may, for example, include a porous metalmedium, a porous ceramic medium, or a porous polymeric medium and may,for example, be in the form of a spirally wound or pleated membrane orsheet, e.g., a fibrous sheet, or a hollow, cylindrical mass, e.g., afibrous mass. Further, the filter medium may have any of a variety ofremoval ratings. For embodiments targeting black powder, the filtermedium may comprise a high-efficiency, high-dirt capacity, tapered-pore,absolute-rated gas depth filter medium. Examples of filter elements thatare particularly effective for removing black powder include filterelements rated 0.3 micron in gas and available under the tradedesignation Coreless from Pall Corporation of Port Washington, N.Y. USA.

The filter assembly 24 may also include a frame 30 for supporting thearray of filter elements 25 in the pressure vessel 11. The frame may beconfigured in any of numerous ways and may support the array for gasflow outside-in or inside-out through the hollow filter elements. Forexample, the frame 30 may support the array for outside-in gas flow andmay include a tube sheet 31 at the end of the array nearer the gasoutlet 16, a support plate 32 closer to, or at, the opposite end of thearray, and one or more struts 33 that connect the tube sheet 31 and thesupport plate 32. The tube sheet 31 and the support plate 32 may have ashape that generally conforms to the cross-sectional shape of theinterior of the pressure vessel and a dimension, e.g., an outerdiameter, that closely corresponds to the inner diameter of the pressurevessel. The tube sheet 31 may have a plurality of openings, and the openend of each filter element 25 may be sealed to an opening in the tubesheet 31, either directly or via a stand-off tube, as shown in FIG. 2.The tube sheet 31 thus defines an unfiltered region of the filterassembly around the filter elements 25 on one side of the tube sheet 31and a filtrate region on the opposite side of the tube sheet 31. Thefiltrate side of the tube sheet 31 may be sealed to a header 34 which,in turn, may be sealed to the gas outlet 16 of the pressure vessel 11.For example, the header 34 may taper to an outlet end that may be sealedto the gas outlet 16. Alternatively, the tube sheet may be sealed to theinterior of the pressure vessel. The support plate 32, which may beconnected to the filter elements 25, for example, at the blind ends ofthe filter elements 25, may also have a plurality of openings, allowingthe unfiltered gas to flow along the exterior of the filter elements 25.

The filter assembly may include one or more additional components. Forexample, the filter assembly may or may not further include a shellsurrounding the array of filter elements and/or a transmit mechanismfacilitating the removal and installation of the filter assembly withinthe pressure vessel. In the embodiment shown in FIG. 2, the filterassembly 24 may not include a shell but may include a transit mechanism35. The transit mechanism may be configured in any of numerous waysincluding, for example, as slides on the filter assembly and/or railsalong the interior of the pressure vessel. In FIG. 2, the transitmechanism 35 may comprise a plurality of wheels 36, e.g., spring loadedwheels, connected to the frame 30 and/or the header 34 and distributedaround the filter assembly 24, allowing the filter assembly 24 to bequickly and conveniently rolled out of and into the interior of thepressure vessel 11.

The separator assembly may be configured in any of numerous ways and mayinclude one or more separators, including, for example, one or moreinertial separators. For many embodiments, the separator assembly maycomprise a multistage separator assembly, and at least one stage mayinclude any type of centrifugal or dynamic separator. One of manydifferent examples of a separator assembly is the two-stage separatorassembly 23 shown in FIG. 3 The first stage may include an impactseparator, e.g., a downwardly angled impact plate 40, directly in thegas flow path from the gas inlet 15 and a large settling region 41 belowthe impact plate 40. The second stage may include one or more higherefficiency separators 42, e.g., a bank of cyclone separators 42supported by a top plate 43. For some embodiments, the cycloneseparators 42 may have a cut off of down to about 8 microns or less atrated gas flow and a cut off of down to about 10 microns or less at 50%of rated gas flow. Any number of cyclone separators may be provided,e.g., four or more, six or more, eight or more, or ten or more, and thecyclone separators may be variously configured. In the embodiment ofFIG. 3, each cyclone separator 42 may include an outer can 44 mountedaround an inner can 45. The outer can 44 may be closed at the inlet end,e.g., by the top plate 43, and open at the lower outlet end, and theinner can 45 may be open at both the inlet and outlet ends, the outletend of the inner can opening through the top plate 43. The axes of thecyclone separators may be oriented parallel to, perpendicular to, or atany angle to the axis of the pressure vessel. In the illustratedembodiment, the axes are generally perpendicular to the axis of thepressure vessel 11. Additional traps may be arranged at and/or below thelower outlet of the outer can to enhance the retention of particulates.

The separator assembly may also include a frame supporting themulti-stage separators, and the frame may be configured in any ofnumerous ways. For example, the frame may comprise a plurality ofsupport plates 50-52 connected by one or more struts 53 as well as thetop plate 43 and the impact plate 40. A downstream support plate 50 maybe positioned at the outlet end of the separator assembly 23, anupstream support plate 51 maybe positioned at the opposite end of theseparator assembly 23, and an intermediate support plate 52 may bepositioned between the upstream and downstream support plates 50, 51.Each support plate 50-52 may have a dimension, e.g., an outer diameter,that closely corresponds to the inner diameter of the pressure vessel11, enabling the support plates 50-52 to fit closely against thepressure vessel 11 and inhibit bypass of any gas around the entireseparator assembly 23 or any of the stages of the separator assembly 23.For some embodiments, one or more of the support plates 50-52 may besealed to the pressure vessel 11. The first stage of the separatorassembly 23 may be defined between the upstream support plate 51 and theintermediate support plate 52, while the second stage may be definedbetween the intermediate support plate 52 and the downstream supportplate 50. An opening in the intermediate support plate 52 beneath theangled impact plate 40 may open into a duct 54 that extends below thetop plate 43, allowing gas to flow from the first stage into the secondstage. The duct 54 may feed the gas to each cyclone separator 42, forexample, through an inlet opening in the side of the outer can 44 nearthe inlet end. An opening in the downstream support plate 50 above thetop plate 43 allows gas to exit the second stage of the separatorassembly 23 and enter the filter assembly 24.

The separator assembly may further include a shell mounted to all or oneor more of the separators and/or stages of the separator assembly tocontain the particulates removed by the separators 40, 42. In theillustrated embodiment, the shell 55 may be mounted to all of theseparators 40, 42 and the frame of the separator assembly 23. The shellmay be variously configured and may or may not be connected and/orsealed to the remainder of the separation assembly. For example, theshell 55 may be generally cylindrical and open on both ends and maysurround one or more of the separators 40, 42. The shell 55 may bedimensioned to fit within the interior of the pressure vessel 11 andaround the separators and support plates 50-52 of the separator assembly23. For example, the shell 55 may be dimensioned to closely correspondto the inner diameter of the pressure vessel 11 and the outer diameterof the support plates 50-52, enabling the shell 55 to inhibit bypass ofany gas between the pressure vessel 11 and the shell 55 or between theshell 55 and the support plates 50-52. For many embodiments, the shell55 may be sealed to the support plates 50-52 in any suitable manner,e.g., permanently or releasably, to contain any particulates removedfrom the gas by the separators 40, 42 of the separator assembly 23. Forexample, the shell 55 may be welded to the outer rims of the separatorplates 50-52 and may form a liquid-tight container containing the solidsand liquids removed from the gas by the separator assembly 23. The shell55 may have a significant liquid and/or solids holding capacity whichallows all of the particulates removed by the separator assembly 23 overan extended period, even after scraping operations, to be convenientlyand safely stored within the shell 55. The shell may have one or moreopenings. For example, the shell 55 may include an inlet opening 57 inthe side, e.g., at the top, of the shell 55 that fluidly communicateswith the gas inlet 15 in the pressure vessel 11, allowing gas to flowthrough the gas inlet 15 into the first stage of the separator assembly23. The inlet opening 57 in the shell 55 may fit closely against the gasinlet 15 and/or may be sealed to the gas inlet 15 to prevent bypass ofgas around the separator assembly 23. Other openings in the shell 55 mayinclude sealable side openings 58 that facilitate emptying and cleaningof the interior of the shell 55 and another top opening 59 that allowsthe shell to be filled with water and/or any other suitable inhibitor.For many embodiments, the shell 55 need not be a pressure vessel capableof withstanding the difference in pressure between the interior and theexterior of the pressure vessel 11. Instead, the shell 55 may be formedfrom a much lighter gauge material, e.g., a lighter gauge metal, thatcan contain solids and liquids removed by the separator assembly 23.

The separator assembly may further include one or more additionalcomponents. For example, the separator assembly may include a transitmechanism facilitating removal and insertion of the separator assemblywithin the pressure vessel or the shell. The transit mechanism may beconfigured in any of numerous ways, including, for example, as slides onthe frame or the shell of the filter assembly and/or rails along thepressure vessel. In the illustrated embodiment, the transit mechanismmay comprise a plurality of wheels 56. The transit mechanism, e.g., thewheels, may be distributed around the frame of the separator assemblyand may be arranged to move, e,g., roll, along the inner periphery ofthe shell 55 in a manner similar to the filter assembly wheels 36. Forexample, outside of the pressure vessel 11 the separators 40, 42 and theframe of the separator assembly 23 may be moved, e.g., rolled, along theinterior of the shell 55 and permanently or removably fixed in place inthe shell 55, for example, by welding the support plates 50-52 to theshell 55. Then the entire separator assembly 23 including the shell 55may be moved through the open hatch 20 of the pressure vessel and fixedin place in any suitable manner with the gas inlet 15 of the pressurevessel 11 fluidly communicating with the inlet opening 57 in the shell55. The shell may further include a transit mechanism, e.g., wheels, tofacilitate this movement along the pressure vessel, or the shell withthe remainder of the separator assembly inside may be guided along thepressure vessel, for example, by a push/pull table similar to thepush/pull tables used for scrapers. Alternatively, the shell may firstbe installed in the pressure vessel without the remainder of theseparator assembly. The remainder of the separator assembly, e.g., theseparators and the frame, may then be moved, e.g., rolled, along theinterior of the shell and fixed in place while the shell is in thepressure vessel.

The purification arrangement may include one or more additionalcomponents. For example, for some, but not all embodiments, thepurification arrangement 10 may include an openable/closable barrier 14positioned in the interior of the pressure vessel 11 between the firstand second purification assemblies 12, 13. The openable/closeablebarrier may be configured in a variety of ways to alternately providefluid communication between the purification assemblies, e.g., thefilter assembly and the separator assembly, and fluidly isolate thepurification assemblies. For example, the barrier 14 may comprise a pairof coaxially mounted plates 60, 61, at least one of the plates 61 beingrotatable. For many embodiments, one plate 60 may be stationary and theother plate 61 may be rotatable. The plates 60, 61 may have a shape thatgenerally conforms to the cross-sectional shape of the interior of thepressure vessel 11 and a dimension, e.g., an outer diameter, thatclosely corresponds to the inner diameter of the pressure vessel 11,providing a close fit between the outer edge of the plates 60, 61 andthe interior of the pressure vessel 11 to inhibit gas flow when thebarrier 14 is closed. The plates 60, 61 may extend generallyperpendicular to the axis of the pressure vessel 11 and may or may notbe sealed to the pressure vessel 11. Each plate 60, 61 may have one ormore apertures extending around a significant portion, e.g., about 50%or less, of the circumference of the plate 60, 61, the remainder of theplate 60, 61 being imperforate. Alternatively, one of the plates 60, 61,e.g., the rotatable plate 61, may be a partial plate having only animperforate portion large enough to obstruct the aperture on the otherplate 60 in the closed position. The barrier 14 may be movable betweenan open position and a closed position. For example, at least one of theplates 61 may rotate with respect to the other plate 60 between the openposition and the closed position. In the open position, the aperture(s)of the plates 60, 61 are aligned and unobstructed, the barrier 14 isopen, and gas may flow through the open barrier 14 between thepurification assemblies 12, 13. For many embodiments, the imperforateportion of the rotatable plate(s) may be oriented gravitationally belowthe aperture(s). The greater weight of the imperforate portion may“lock” the barrier in the open position during normal operation when gasflows between the purification assemblies. Alternatively oradditionally, the plates may be locked in the open position by a lockingmechanism (not shown). In the closed position, the imperforate portionsof the plates 60, 61 obstruct the apertures of the plates 60, 61, thebarrier 14 is closed, and the purification assemblies 12, 13 are fluidlyisolated from one another. The plates 60, 61 may be sealed to oneanother or may be positioned sufficiently close to one another tosubstantially inhibit gas flow through the obstructed apertures of theclosed barrier.

The barrier 14 may be mounted in the gas flow path between thepurification assemblies in a wide variety of ways. For example, thebarrier 14 may include a mount 62 for supporting the barrier 14 in thegas flow path between the first and second purification assemblies 12,13. The mount 62 may be variously configured and the plates 60, 61 maybe supported by the mount 62 in a variety of ways, e.g., rotatablysupported. The mount may be attached to a variety of structures tosupport the barrier in the interior of the pressure vessel. For someembodiments, the mount may be attached to the pressure vessel itself.For example, the mount may be attached, e.g., removably attached, to theinterior of the pressure vessel, supporting the barrier between thefilter assembly and the separator assembly. For other embodiments, themount may be attached to the separator assembly. For example, the mountmay be attached to the struts or the downstream support plate of theframe or to the shell of the separator assembly, supporting the bagfirer just beyond and downstream of the separator assembly. For stillother embodiments, the mount may be attached directly to the filterassembly 24. For example, the mount 62 may be attached to the frame 30of the filter assembly 24, e.g., the support plate 32 and/or the struts33, supporting the barrier 14 just behind and upstream of the filterassembly 24.

Methods for removing particulates from a gas flowing in a gas pipelinesystem may be embodied in a wide variety of ways. For example, duringnormal operation a flow of gas may be established through the pipelinesystem and through the pressure vessel 11 connected to the pipeline. Asthe gas flows along the gas flow path through the interior of thepressure vessel 11, the gas is directed through the gas inlet 15, thefirst purification assembly 12, and the second purification assembly 13before exiting the pressure vessel 11 via the gas outlet 16. Forembodiments having a barrier 14, the gas may also be directed throughthe open barrier 14 between the purification assemblies 12, 13. As thegas flows through the purification assemblies 12, 13, a significantportion of the particulates, both liquid and solids, is removed from thegas by the purification assemblies 12, 13. A wide variety of differentpurification assemblies may be contained in the pressure vessel toremove particulates from the gas, as previously explained. One ofnumerous examples of different combinations of purification assembliesis shown in FIG. 1, where the first purification assembly 12 maycomprise a separator assembly 24 for removing liquid and larger solidsparticulates and the second purification assembly 13 may comprise afilter assembly 24 for removing finer solids particulates. Thisarrangement of a separator assembly 23 upstream and a filter assembly 24downstream in the pressure vessel 11 is particularly effective forremoving black powder from the gas.

As shown in FIG. 1, gas may enter the pressure vessel 11 and pass alongthe gas flow path first through the separator assembly 23 and thenthrough the filter assembly 24. As the gas passes through the separatorassembly 23, it may be first directed through the first stage of theseparator assembly to remove liquid and larger solids particulates andthen through the second stage to remove additional liquid and finersolid particulates. For example, gas may pass from the gas inlet 15directly to the first stage, impinging against an impact separator,e.g., the angled impact plate 40. Liquid particulates may coalesce alongthe impact plate 40 and then flow to the bottom of the first stage. Thelarger solids particulates may be deflected by the impact plate 40 tothe side and then fall to the bottom of the first stage. After movingquickly past the edges of the angled impact plate 40, the gas may slowin the larger settling region 41 below the angled impact plate 41,allowing additional particulates to settle to the bottom of the firststage. As the particulates are removed by the separator(s) of the firststage, the shell may collect and contain the removed particulates. Forexample, the particulates removed in the first stage may be containedbetween the upstream support plate 51 and the intermediate support plate52 by the shell 55, thereby isolating the particulates from the pressurevessel 11.

The gas may then enter the second stage from the settling region 41 ofthe first stage, for example, passing through an aperture locatedclosely under the apex of the angled impact plate 40 and into the duct54 of the second stage. From the duct 54, the gas may enter a cycloneseparator 42, for example, through an inlet opening in the side of eachouter can 44, where the gas and remaining liquid and solids particulatesare swirled within the outer can 44 toward the outlet end of the can 44.Liquid and solids particulates are deflected from the principal gas flowstream by the cyclonic movement of the gas in the outer can 44 and fallto the bottom of the second stage through the outlet end of the outercan 44. Additional traps (not shown) beneath the outer cans may enhancethe retention of liquid and solid particulates between the intermediateand downstream support plates 52, 50. The gas may pass from the outletend of the outer can 44 and into the inlet end of the inner can 45,where it may pass along the inner can 45 and through the outlet end ofthe inner can 45 into the space above the top plate 43. From the spaceabove the top plate 43, the gas, substantially depleted in particulates,may exit the separation assembly 23, for example, through the opening inthe downstream support plate 50 above the top plate 43. Again, as theparticulates are removed by the separators of the second stage, theshell may collect and contain the removed particulates. For example, theparticulates removed in the second stage may be contained between theintermediate support plate 52 and the downstream support plate 50 by theshell 55, isolating the particulates from the pressure vessel 11.

From the first purification assembly 12, e.g., the separator assembly23, the gas may flow along the gas flow path to the second purificationassembly 13, e.g., the filter assembly 24. For embodiments having anopenable/closeable barrier 14, the gas may flow between the purificationassemblies 12, 13, e.g., the separator and filter assemblies 23, 24,through an open barrier 14. For example, the gas may flow through thealigned apertures in the plates 60, 61 of the open barrier 14 betweenthe separator assembly 23 and the filter assembly 24 with little or nopressure drop. For embodiments without an openable/closable barrier, thegas may flow directly to the second purification assembly.

From the first purification assembly 12, the gas may pass along the gasflow path through the filter assembly 24, where any finer particulatesremaining in the gas may be removed by the filter medium 26. Forexample, for embodiments arranged fix outside-in flow through the filterelements 25, the gas may flow into the unfiltered region along theexterior of the filter elements 25. The gas then passes outside-inthrough the porous filter medium 26 of each filter element 25, where thefiner particulates are removed by the filter medium 26, and into theinterior of the hollow filter clement 25. From the interiors of thefilter elements 25, the filtered gas may pass to the gas outlet 16 ofthe pressure vessel 11 substantially free of liquid and solidsparticulates. For example, the gas may pass along the interiors of thefilter elements 25 through the apertures in the tube sheet 31 into theheader 34 and through the header 34 to the gas outlet 16.

After an extended period of time, one or both of the purificationassemblies 12, 13, e.g., the separator assembly 23 and/or the filterassembly 24, may become loaded with particulates. Various sensors, e.g.,pressure sensors and/or weight sensors, associated with the purificationassemblies 12, 13 may provide an indication that a design parameter,e.g., the pressure drop across or the particulate weight within thepurification assembly, has been exceeded. Gas flow through the pressurevessel 11 may then be terminated. For example, the pipeline system maybe shut down or the purification arrangement 10 may be bypassed or takenoff line in favor of a parallel purification arrangement 10. Upontermination of the gas flow one or both of the purification assemblies12, 13 as well as the pressure vessel 11 may be serviced, e.g., cleanedand/or replaced.

The shell 55 of the separator assembly 23 greatly facilitates servicingof the purification arrangement 10. Many particulates, including blackpowder, may be toxic and/or may be chemically reactive, e.g.,pyrophoric, when exposed to air and, therefore, present a serious safetyhazard to the service personnel. The shell 55 collects and contains theparticulates removed by the separators 40, 42 and isolates the servicepersonnel from many of the hazards of these particulates. For example,in the illustrated embodiment, the pressure vessel 11 may be opened,e.g., by swinging the hatch 20 open, and the separator assembly 23 maybe removed through the open hatch 20. The separator assembly 23,including the shell 55, may be removed from the pressure vessel 11, forexample, via a transit mechanism and/or a push/pull table, with all ofthe collected liquid and solid particulates contained within the shell55 and isolated from the service personnel. To even further ensure thesafety of the service personnel, the shell may be filled with waterand/or any other suitable inhibitor. For example, water may dilute theliquid contaminants and prevent any solid contaminants from reactingwith air. The water may be supplied to the shell 55 through a waterinlet in the pressure vessel 11 and the top opening 59 in the shell 55before the separator assembly 23 is removed.

In addition to protecting the service personnel, the shell 55 of theseparator assembly 23 greatly reduces the downtime required for removinga separator assembly 23 fully loaded with particulates and replacing itwith a cleaned/new separator assembly 23 empty of particulates. Not onlydoes the shell 55 isolate the particulates from the service personnel,it also isolates the particulates from the pressure vessel 11. When theloaded separator assembly 23 with all of the removed particulatescontained within the shell 55 is removed, the pressure vessel remainsrelatively clean, requiring far less time to clean the interior of thepressure vessel 11 in the vicinity of the removed separator assembly 23and install the cleaned/new separator assembly 23.

For embodiments having an openable/closeable barrier, service personnelmay be further protected by the openable/closeable barrier 14. Forexample, after the gas flow is terminated, the open barrier may beclosed, isolating the purification assemblies from one another andallowing at least one of the purification assemblies e.g., the separatorassembly 23, to be serviced without exposing the service personnel tothe particulates in the other purification assembly, e.g., the filterassembly 24. For example, the hatch 20 of the pressure vessel 11 may beopened and the open barrier 14 may be moved to the closed position inany of a variety of ways. For example, one of the purificationassemblies, e.g., the separator assembly 23, may have a hollow guide 63which extends through the purification assembly 11 and allows a tool 64,e.g., an elongate T-bar, to be coupled to the open barrier 14 to move itto the closed position. For some embodiments, the tool 64 may have afitting on one end that engages the rotatable plate 61 of the barrier 14and rotates the plate 61 until the imperforate portions of the plates61, 62 obstruct the apertures in the plates 61, 62, closing the barrier14. The closed barrier 14 defines first and second isolated chambers 65,66 within the pressure vessel 11 around the first and secondpurification assemblies 12, 13 respectively, allowing the servicepersonnel to service one of the purification assemblies 12, 13 free ofthe risks from the particulates in the other purification assembly 13,12.

For many embodiments, the service personnel may be even furtherprotected by flooding one or both of the first and second chambers 65,66 with an inert gas, e.g., nitrogen. For some embodiments, before thehatch 20 is opened, the entire pressure vessel 11 or at least the secondchamber 66 may be flooded with the inert gas via an inert gas inlet inthe pressure vessel 11. The hatch 20 may then be opened and the barrier14 may be moved to the closed position, maintaining the inert gas in thesecond chamber 66 around the filter elements 25 of the filter assembly24. Additionally, a small flow of inert gas may be directed into thesecond chamber 66 to maintain a small positive pressure of inert gas inthe second chamber 66 while barrier 14 is closed and the firstpurification assembly 12, e.g., the separator assembly 23, is removedand/or serviced. Maintaining the inert gas around the secondpurification assembly 13, e.g., the filter assembly 24, ensures that thefine particulates removed by the filter assembly 24 are not exposed toair and subject to the possibility of a pyrophoric reaction.

If the second purification assembly 13 is not in need of servicing, acleaned/new first purification assembly 12, e.g., a separator assembly23, may be installed through the open hatch 20 in the pressure vessel11, e.g., via a transit mechanism and/or push/pull table. Forembodiments having an openable/closeable barrier 14, the closed barrier14 may be opened, either before or after the cleaned or new firstpurification assembly is installed. For example, a cleaned/new separatorassembly 23 including a shell 55 may be installed in the pressure vessel11. The T-bar 65 may be inserted through the guide 63 and engaged withthe rotatable plate 61, and the plate 61 may be rotated until theapertures in the plates 60, 61 are aligned, opening the barrier 14 fornormal operation. The cover, e.g., the hatch 20, may be closed and gasflow may again be established through the purification arrangement 10.

If the second purification assembly 13 is also in need of servicing, ittoo may be removed from the pressure vessel 11. For some embodiments,the pressure vessel may include a separate opening, e.g., a separatehatch or cover, for removing the second purification assembly allowingthe second purification assembly to be removed before or at the sametime as the first purification assembly. In the illustrated embodiment,the second purification assembly 13, e.g., the filter assembly 24, maybe removed from the pressure vessel 11 after the first purificationassembly 12, e.g., the separator assembly 23, through the same opening,e.g., the hatch 20, as the first purification assembly 12. Forembodiments in which an openable/closeable barrier is attached directlyto the pressure vessel, the barrier and/or the barrier mount may beremoved from the pressure vessel before the second purification assemblyfollows the first purification through the hatch. For embodiments inwhich the barrier 14 is attached to the first or second purificationassembly 12, 13 or no battier is provided, the second purificationassembly 13 may be removed from the pressure vessel 11 for cleaning orreplacement in a variety of ways, as previously described with respectto the first purification assembly 12. In the illustrated embodiment,the filter assembly 24 may be disengaged from the gas outlet 16 of thepressure vessel 11, for example, by disengaging the header 34 from thegas outlet 16. For embodiments with a transit mechanism, e.g., thewheels 36, the filter assembly 24 may be quickly and easily rolled alongthe pressure vessel 11 through the open hatch 20. The barrier 14 may beremoved from the pressure vessel 11, for example, along with the filterassembly 24. The individual filter elements 25 may be cleaned orreplaced. Alternatively, an entirely new filter assembly 24, includingnew filter elements 25, with or without a barrier 14, may replace thespent filter assembly 24.

Once the pressure vessel 11 is empty, it may be cleaned and acleaned/new second purification assembly 13 may be installed in thepressure vessel 11. For example, the cleaned/new filter assembly 24,with or without an attached barrier 14, may be moved into the pressurevessel 11 through the open axial end and along the pressure vessel 11and fitted into sealed engagement with the gas outlet 16 at the oppositeend of the pressure vessel 11. For embodiments with a transit mechanism,e.g., the wheels 36, the filter assembly 24 may be quickly and easilyrolled toward the gas outlet 16 until the header 34 engages and issealed to the gas inlet 16.

Before or after the cleaned/new second purification assembly 13, e.g.,the filter assembly 24, is installed, any barrier 14 may be moved to theopen position. The cleaned/new first purification assembly 12, e.g., theseparator assembly 23, may then be installed as previously described.The cover, e.g., the hatch 20 may be closed. And a gas flow may again beestablished through the purification arrangement 10.

Although the invention has been disclosed in the embodiments previouslydescribed and illustrated, the invention is not limited to thoseembodiments. For instance, one or more features of an embodiment may beeliminated or modified, one or more features of one embodiment may becombined with one or more features of other embodiments, or embodimentswith very different features may be envisioned without departing fromthe scope of the invention. For example, for some embodiments theopenable/closeable barrier may comprise a single plate including onesection hinged to another section. The hinged section may be movedbetween a closed position and an open position. In the closed position,the two sections of the plate may be co-planar and the plate may have ashape that closely fits across the cross section of the pressure vessel,inhibiting gas flow and isolating the first and second purificationassemblies. In the open section, the hinged sections may extend at anangle to one another, creating an aperture through which gas may flowbetween the first and second purification assemblies. A tool similar tothe T-bar may be used to open and close the hinged barrier. For someembodiments, the barrier may comprise a shuttered or louvered plate. Theshutter(s) or louver(s) may be moved to an open or closed position in avariety of ways, including for example, as previously described withrespect to the T-bar. Alternatively, the shutter(s) or louver(s) may bebiased toward a closed position, e.g., by springs, but forced to theopen position when the first purification assembly is inserted in thepressure vessel. For example, a member on the first purificationassembly may contact the barrier and force the shutter(s) or louver(s)open when the first purification assembly is properly positioned in thepressure vessel.

For some embodiments, the array of filter elements may be arranged forgas flow inside-out. The tube sheet may be positioned at the end of thearray closest to the barrier and may be sealed to the pressure vessel orto a housing surrounding the array of filter elements. The open ends ofthe filter elements may be sealed to the apertures in the tube sheet,while the support plate may be located at or near the opposite end ofthe array. Gas flowing through the open barrier may pass into theinteriors of the hollow filter elements through the apertures in thetube sheet and then pass inside-out through the filter medium, where thefiner particulates are removed, to the exterior of the filter elements.From the exterior of the filter elements, the gas may pass to the gasoutlet of the pressure vessel.

The present invention thus encompasses innumerable embodiments and isnot restricted to the particular embodiments that have been described,illustrated, and/or suggested herein. Rather, the present inventionincludes all embodiments and modifications that may fall within thescope of the claims.

The use of the terms “a” and “an” and “the” and “at least one” andsimilar referents in the context of describing the invention (especiallyin the context of the following claims) are to be construed to coverboth the singular and the plural, unless otherwise indicated herein orclearly contradicted by context. The use of the term “at least one”followed by a list of one or more items (for example, “at least one of Aand B”) is to be construed to mean one item selected from the listeditems (A or B) or any combination of two or more of the listed items (Aand B), unless otherwise indicated herein or clearly contradicted bycontext. The terms “comprising,” “having,” “including,” and “containing”are to be construed as open-ended terms (i.e., meaning “including, butnot limited to,”) unless otherwise noted. Recitation of ranges of valuesherein are merely intended to serve as a shorthand method of referringindividually to each separate value falling within the range, unlessotherwise indicated herein, and each separate value is incorporated intothe specification as if it were individually recited herein. All methodsdescribed herein can be performed in any suitable order unless otherwiseindicated herein or otherwise clearly contradicted by context. The useof any and all examples, or exemplary language (e.g., “such as”)provided herein, is intended merely to better illuminate the inventionand does not pose a limitation on the scope of the invention unlessotherwise claimed. No language in the specification should be construedas indicating any non-claimed element as essential to the practice ofthe invention.

Preferred embodiments of this invention are described herein, includingthe best mode known to the inventors for carrying out the invention.Variations of those preferred embodiments may become apparent to thoseof ordinary skill in the art upon reading the foregoing description. Theinventors expect skilled artisans to employ such variations asappropriate, and the inventors intend for the invention to be practicedotherwise than as specifically described herein. Accordingly, thisinvention includes all modifications and equivalents of the subjectmatter recited in the claims appended hereto as permitted by applicablelaw. Moreover, any combination of the above-described elements in allpossible variations thereof is encompassed by the invention unlessotherwise indicated herein or otherwise clearly contradicted by context.

The invention claimed is:
 1. A purification arrangement for a gaspipeline system, the purification arrangement comprising: a pressurevessel including an interior, a gas inlet, and a gas outlet and defininga gas flow path through the interior of the pressure vessel between thegas inlet and the gas outlet, wherein the pressure vessel includes anopenable cover; a first purification assembly located in the pressurevessel in the gas flow path between the gas inlet and the gas outlet; asecond purification assembly located in the pressure vessel in the gasflow path between the gas inlet and the gas outlet, the secondpurification assembly being located in the gas flow path between the gasoutlet and the first purification assembly, wherein at least one of thefirst and second purification assemblies includes a separator assemblyhaving one or more separators for removing particulates from the gas anda shell mounted to the one or more separators to contain theparticulates removed by the one or more separators, and wherein theseparator assembly including the shell is removable from the pressurevessel via the openable cover.
 2. The purification arrangement of claim1 wherein the first purification assembly comprises the separatorassembly.
 3. The purification arrangement of claim 1 wherein theseparator assembly includes one or more cyclone separators.
 4. Thepurification arrangement of claim 1 wherein the separator assemblyincludes a plurality of stages positioned in the gas flow path, whereinat least one of the stages includes one or more cyclone separators. 5.The purification arrangement of claim 4 wherein the shell surrounds allstages of the separator assembly.
 6. The purification arrangement ofclaim 1 wherein at least one of the first and second purificationassemblies comprises a filter assembly having a porous filter medium forfiltering particulates from the gas.
 7. The purification arrangement ofclaim 6 wherein the filter assembly comprises an array of hollow,cylindrical filter elements.
 8. The purification arrangement of claim 1further comprising an openable/closable barrier positioned in theinterior of the pressure vessel between the first and secondpurification assemblies, the barrier being moveable between an openposition wherein the first purification assembly fluidly communicateswith the second purification assembly and a closed position wherein thebarrier isolates the first and second purification assemblies from oneanother.
 9. A purification arrangement for a gas pipeline system, thepurification arrangement comprising: a pressure vessel including aninterior, a gas inlet, and a gas outlet and defining a gas flow paththrough the interior of the pressure vessel between the gas inlet andthe gas outlet, wherein the pressure vessel includes an openable cover;a filter assembly located in the gas flow path in the interior of thepressure vessel, wherein the filter assembly includes a plurality offilter elements, each element including a filter medium for filteringparticulates from gas flowing through the filter element; and aseparator assembly located in the gas flow path in the interior of thepressure vessel between the gas inlet of the pressure vessel and thefilter assembly, wherein the separator assembly comprises one or moreseparators for removing particulates from the gas and a shell mounted tothe one or more separators to contain the particulates removed by theone or more separators, and wherein the separator assembly including theshell is removable from the pressure vessel via the openable cover. 10.The purification arrangement of claim 9 wherein the separator assemblyincludes one or more cyclone separators.
 11. The purificationarrangement of claim 9 wherein the separator assembly comprises at leasta first stage and a second stage downstream from the first stage in thegas flow path, the second stage including cyclone separators.
 12. Thepurification arrangement of claim 11 wherein the shell surrounds boththe first and second stages and collects particulates removed by thefirst and second stages.
 13. The purification arrangement of claim 9wherein the shell defines a liquid-tight enclosure.
 14. The purificationarrangement of claim 9 wherein each filter element has a hollow,cylindrical configuration and the plurality of filter elements arearranged for outside-in flow.
 15. The purification assembly of claim 9further comprising an openable/closable barrier positioned in theinterior of the pressure vessel between the filter assembly and theseparator assembly, the barrier being moveable between an open positionwherein the filter assembly fluidly communicates with the separatorassembly and a closed position wherein the barrier isolates the filterassembly and the separator assembly from one another.
 16. A method forremoving particulates from a gas flowing in a gas pipeline system, themethod comprising: establishing a flow of gas through a pressure vesselfrom a gas inlet to a gas outlet, including directing gas through afirst purification assembly and a second purification assembly, whereindirecting gas through the first purification and second purificationassemblies includes directing gas through one or more separators forremoving particulates from the gas and containing the particulatesremoved by the one or more separators in a shell mounted around theseparators; terminating the flow of gas through the pressure vessel; andservicing at least one of the first and second purification assemblies,including opening an openable cover of the pressure vessel and removingfrom the pressure vessel the one or more separators and the shellcontaining the particulates removed by the one or more separators viathe openable cover.
 17. The method of claim 16 further comprisingfilling the shell with water after terminating the flow of gas throughthe pressure vessel.
 18. The method of claim 16 wherein directing gasthrough the first purification assembly comprises directing the gasthrough the separator assembly and wherein directing gas through thesecond purification assembly comprises directing gas through a filterassembly downstream from the separator assembly.
 19. The method of claim16 wherein establishing the flow of gas includes directing gas throughan open barrier positioned between first and second purificationassemblies, the method further comprising closing the barrier to fluidlyisolate the first and second purification assemblies after the flow ofgas has been terminated.
 20. The method of claim 16 further comprisingreestablishing a gas flow through the pressure vessel after servicing atleast one of the first and second purification assemblies.
 21. Thepurification arrangement of claim 4 wherein the separator assemblyincludes support plates separating the stages and wherein the shell ismounted around the support plates to inhibit gas flow between the shelland the support plates.
 22. The purification arrangement of claim 1wherein the openable cover comprises an openable hatch at an axial endof the pressure vessel.
 23. The purification arrangement of claim 11wherein the separator assembly includes support plates separating thestages and wherein the shell is mounted around the support plates toinhibit gas flow between the shell and the support plates.